Two-way lamp with thermal switch



Jan. 4, 1966 S. C. PEEK, JR.. ETAL TWO-WAY LAMP WITH THERMAL SWITCH Filed Aug. 4. 1960 BRIGHT CLOSED POSITION E W L OPEN POSITION INVENTORS SANDFORD C. PEEK, JR. DANIEL S. GUSTIN DAVID R. DAYTON KENWAY, JENNEY, WITTER & HIL'JRETH ATTORNEYS United States ?atent O l TWO-WAY LAMP WHTH THERMAL SWITCH Sandford C. Peek, .lr., Hamilton, Daniel S. Gustin, Topstieid, and David R. Dayton, Beverly, Mass., assignors to ylvania Electric Products Inc, a corporation of Delaware Filed Aug. 4, 1960, Ser. No. 47,518 3 (Ilaims. (Cl. 315-66) This invention relates in general to incandescent lamps and in particular to a two-way lamp which provides a bright light for reading or a mild light for soft room illumination.

Market research has indicated that in other than work areas two principal forms of lighting are Wanted for residential lighting purposes. For reading, a bright intense light is preferred, but for general room illumination, a softer light is usually desired. A light substantially white in color temperature serves best for reading, but the light preferred for general room illumination is one having a reddish or candelight tone. A considerable effort has been made to provide both types of lighting, the relatively recently developed soft light having achieved considerable acceptance, while reading lamps offering a bright white light continue to sell in large quantities. These, though, are independent lamps. On the other hand, various so-called three-way lamps are available These usually contain two filaments. Switching steps are provided in the socket, and the first step connects a low wattage filament to the line. The second connects a high wattage filament to the line; and the third places both filaments in parallel across the line. In these lamps, the light intensity changes with switch position, but each output is of approximately the same color temperature as the others. Furthermore, the low wattage filament is necessarily formed of relatively fine wire and is subject to relatively short life.

The present invention has as its primary object the provision of an efiicient reading light and a soft illuminating light in the same lamp.

It is a further object of the present invention to provide a more rugged and durable dual purpose lamp than those presently available.

It is a still further object of the present invention to provide dual purpose lamps for use in standard screw-in lamp sockets and in standard three-way lamp sockets.

In general, the invention is organized about a lamp having a pair of filaments so mounted and connected that one filament may be operated to produce bright white light, and two may be operated in series to produce a soft relatively dim light. The lamp designed for operation in a three-way socket provides a bright white light in the first position, a soft warm light in the second position, and a bright white light again in the third position. The fourth switching step extinguishes the light.

In the lamp designed for use in a standard screw-in socket, switching is accomplished within the lamp itself. A bimetallic element cooperates with a latching spring to provide a bright white light from one filament when the lamp switch is first turned on. After a few seconds elapse, the lamp may be turned off and then on again. At this second actuation a warm soft light is produced by the two lamp filaments in series. The lamp may then be turned off, and the light is extinguished while the lamp returns to its original condition, reset for further cycling. For a better understanding of the present invention together with other and further objects, features and advantages, reference should be made to the following detailed description of preferred embodiments thereof which should be read in conjunction with the attached drawings in which:

3,227,920 Patented Jan. 4, 1966 FIG. 1 is a sectional view of a two-way lamp made in accordance with the invention for use in a standard screwin socket,

FIGS. 2 and 3 are fragmentary and partially schematic views of the lamp of FIG. 1 showing various steps of lamp energization, and

FIG. 4 is a fragmentary and partially schematic view of a two-way lamp made in accordance with the invention for use in a three-way lamp socket.

In FIG. 1, a lamp made in accordance with the inven tion is shown in the form which it takes for use in a standard screw-in socket. In this instance, only a conventional on-ofi switch is used, switching of the light output being done within the lamp by means of a bimetallic strip 12 and a latch spring 13, which is attached to the support wire 28, which in turn is attached to the filament support wire 29. The latch spring is in the form of a strip which has a portion approximately transverse to the axis of the lamp and a portion at right angles to that portion, and extending up toward the free end of the bimetallic strip 12, which is welded or otherwise afiixed to the otherwise free end of support wire 28. The latch spring 13 is bent at its own free end to form a J-shaped end, just below the free end of bimetallic strip 12, so that it will snap over the end of said strip when the latter is deflected downward by heating and hold it as shown in FIG. 3. The U-shaped member 30 acts as a stop to limit the upward movement of latching spring 13 as the bimetal 12 moves upwardly after latching. When the stop is reached, further upward movement of the bimetal 12 trees it from the latch, as is clear from its position as shown in FIG. 3. The lead-in wire 33 supports one end of filament 14.

When the switch is first turned on, the line is connected across only the first of two filaments l4 and 15 since the bimetallic strip 12 is normally in open circuit position. The filament 14 then provides a bright white light and a relatively large quantity of heat. The heat produced by the filament 14 is effective upon the bimetal strip 12 to cause that strip to bend downwardly as it is seen in the drawing. The bimetal strip contacts the latch formed adjacent the end of the latch spring 13, and after a few seconds elapse, it is actually beneath and engaged by the latch portion. This movement of the bimetal strip is made possible by the configuration of the latch and the fiexibility of the spring. The latch is pushed back by the end of the bimetal strip 12 to permit its passage beyond the latch.

The position of the bimetal strip 12 at this point in its cycle is shown in FIG. 2. As is also shown schematically in FIG. 2, a line switch 17 is provided to connect the lamp to the line. Actually, the switch would conventionally be mounted on a socket which contains the lamp base, but these details havebeen indicated schematically for convenience. With the switch 17 closed for the first time, however, the filament 14 only is placed across the line, and is provides a brilliant white light, as previously indicated,

Now, if the switch 17 is reopened, the line is disconnected from the filament 14 and heat output from that filament rapidly declines. The bimetal strip 12 quickly cools and commences to swing upwardly toward its original position. As the strip 12 swings upwardly, it carries the latch spring 13 with it, opening the contacts 31, 32 between the latch spring 13 and the lead 16 to which one side of the line is connected. If the switch 17 is once more turned on in the manner illustrated in FIG. 3, current flows again from the line, but in this instance through the series connected filaments 14 and 15. The filaments 14 and 15 are now in series across the line, and their light output is relatively dim and of a softer, more red color temperature. Since the light output is now dim, the

temperature of the filaments is necessarily low, and as shown in FIG. 3, the amount of heat from them is insufiicient to deflect the bimetal back to allow the contacts 31, 32 to close. If the amount of heat were sufiicient to close these contacts, flashing on-and-ofi might result.

Finally, if the switch is turned once more, the light is entirely extinguished, and after a few more seconds elapse, the bimetal strip 12 is cooled to such a degree that it forces itself from under the latching end of the spring 13 and resumes its original position.

In a typical device built in accordance with the invention, the source of voltage is conventional 60 cycle 117 volt AC. The filaments are substantially identical and may be rated at 150 watts each and designed for operation at the line voltage cited.

In FIG. 4, a lamp made in accordance with the present invention for use in a conventional three-way socket is fragmentarily shown. As in the embodiment of the invention shown and described above, two filaments 14 and 15 are provided. These may be identical to those described above and they may be jointly connected as shown to a support lead 16 and severally connected at their opposite ends to support leads 18 and 19. These leads in turn are connected to the ring, the button, and the shell respectively of a conventional three-way lamp base.

The three-way base fits a socket which has complementary contacts for the button, ring, and shell of the base and a switch for making connections to the line in proper sequence. The switch is generally schematically indicated at 27, and it is of a multiple position design. In the first position, the switch is open. In the second position, indicated by the dotted lines, current flows from the line, through a ring contact R to the lead 16, the filament 14 and the lead 19 to the button, thence to the line. In this position only the filament 14 is energized, and a bright white light is produced.

The third switch position is that indicated by the heavy dark lines in the switch 27. In this instance, current flows from the line, through the shell contact S and the contact lead 18, to the filaments 15 and 14 in series, through the lead 19, the button, and thence back to the line. With the two filaments connected thus in series, a dim, warm red light is produced.

In the fourth position of the switch, the double selector of the switch 27 connects the ring contact R and the shell contact S together to one side of the line. This results in current flowing only through the filament 14 because the filament 15 is then bypassed by the low resistance of the lead 16, Again, with a single filament energized, a bright white light is produced.

Although what has been described constitute preferred structures for accomplishing the dual objectives of the invention, other and further modifications and adaptations will suggest themselves to those skilled in the art. As one example of the many possible variations in structure, diiferent lighting effects may be obtained by utilizing filaments which are of different values. The invention should therefore be limited not to the exact details of the embodiment shown, but only by the spirit and scope of the appended claims.

What is claimed is:

1.. In a lighting system, in combination, a source of voltage, a first filament, a second filament and a manual switch normally connected in series, and a normally closed heat-responsive switch forming a shunt path around said second filament and in series with said first filament and said source of voltage, first closing of said manual switch energizing said first filament from said source of voltage, heat from said first filament conditioning said heat-responsive switch to open upon subsequent cooling, reopening of said manual switch causing said heat-responsive switch to open, and reclosing of said manual switch placing said first and said second filaments in series with said source of voltage.

2. A lighting system as set forth in claim 1 in which said heat-responsive switch comprises a bimetallic element and means engageable by said bimetallic element, said means being movable in response to cooling of said bimetallic element to break said shunt path around said second filament.

3. In a lighting system as defined in claim 1, said heat-responsive switch comprising a bimetallic element in position to be heated by the passage of current through said first filament, and latching means engageable by said bimetallic element and normally holding a pair of contacts closed to short-circuit said second filament, said bimetallic element being normally between said latching means and said first filament and being moveable to the opposite side of said latching means when heated by said filament, and adapted on cooling to engage said latching means and carry it with it toward said first filament, thereby opening said contacts and placing the two filaments in series, the amount of heat from the filaments in series being insuificient to move said bimetallic element enough to allow said contacts to close, the amount of heat from the filaments in series being insufficient to move said bimetallic element enough to allow said contacts to close.

References Cited by the Examiner UNITED STATES PATENTS 603,705 5/1898 Phelps 315-66 625,219 5/1899 Truitt 315-66 635,058 10/1899 Phelps 315-66 732,644 6/1903 Lobenthal et a1 315-66 2,235,360 3/1941 Davis 315- 2,448,493 8/1948 Meno et a1 315-65 FOREIGN PATENTS 156,333 6/1939 Austria.

, GEORGE N, WESTBY, Primary Examiner.

RALPH G. NILSON, Examiner. 

1. IN A LIGHTNING SYSTEM, IN COMBINATION, A SOURCE OF VOLTAGE, A FIRST FILAMENT, A SECOND FILAMENT AND A MANUAL SWITCH NORMALLY CONNECTED IN SERIES, AND A NORMALLY CLOSED HEAT-RESPONSIVE SWITCH FORMING A SHUNT PATH AROUND SAID SECOND FILAMENT AND IN SERIES WITH SAID FIRST FILAMENT AND SAID SOURCE OF VOLTAGE, FIRST CLOSING OF SAID MANUAL SWITCH ENERGIZING SAID FIRST FILAMENT FROM SAID SOURCE OF VOLTAGE, HEAT FROM SAID FIRST FILAMENT CONDITIONING SAID HEAT-RESPON- 